This line was started thirteen years ago by the publication of the first three volumes, The Rover Boys at School, On the Ocean, and In the Jungle. I hoped that the young people would like the stories, but I was hardly prepared for the very warm welcome the volumes received. The three books were followed by a fourth, The Rover Boys Out West, and then, yearly, by On the Great Lakes, In Camp, On Land and Sea, On the River, On the Plains, In Southern Waters, On the Farm, On Treasure Isle, At College, and then by Down East, where we last left our heroes and their friends.